1. Field of the Invention
The present invention relates to an image processing apparatus and image processing method, particularly to an image processing technique of detecting a personal face from an image and performing personal authentication for the detected face.
2. Description of the Related Art
In recent years, still cameras capable of performing personal authentication have been introduced, which periodically detect a face during shooting and compare it with personal information held in advance, thereby identifying whose the face is. Such a camera performs face detection a number of times per second. After the face detection, personal authentication is executed using the detection result. Personal authentication processing takes a longer time than face detection. Hence, face detection is performed a number of times during that time.
However, the detected face is not necessarily optimal for personal authentication. For example, the face may tilt or include eye closure. In this case, no reliable personal authentication result can be obtained.
As an optimal face detection method to solve this problem, Japanese Patent Laid-Open No. 2008-310775 describes an image processing apparatus which determines the detection result each time while performing face detection, and uses only a face satisfying conditions for facial expression recognition. Using only a face satisfying conditions for facial expression recognition enables to extract an optimum face.
However, when performing personal authentication of the above-described related art, the start of personal authentication delays because it is necessary to wait for the face detection result to satisfy the predetermined conditions. For this reason, the time to obtain the personal authentication result may be longer.